Experiments are designed to elucidate the protein composition of the pigment epithelial cell plasma membrane from both normal and RCS rats. The common goal of these studies is to determine if the RCS mutation results in retinal degeneration by affecting the production of a plasma membrane protein that is involved in the recognition and phagocytosis of shed rod outer segment (ROS) discs. utilizing sensitive cell surface labeling techniques, two dimensional gel electrophoresis and autoradiography, the protein composition of plasma membranes, isolated from cultured pigment epithelial (PE) cells from both normal and RCS rats, will be analyzed and compared. Phagosomes will be isolated from surface-labeled pigment epithelial cells to determine which plasma membrane proteins are involved in phagocytosis. Pigment epithelial cell plasma membranes and soluble components from normal and RCS rats will be assayed for endogenous lectins (sugar binding proteins) that may play a role in pigment epithelial cell-ROS recognition and interaction. The long term objective of these studies is to better understand the cause of inherited retinal degeneration on a molecular level, especially with regard to surface interactions between pigment epithelial cells and the photoreceptors.